Field of the Invention
The present invention relates to a motor controller that performs speed sensorless control for an induction motor.
Related Art
A motor controller that drives and controls an induction motor is classified into a motor controller that uses a speed sensor such as a rotary encoder and a motor controller that performs so-called speed sensorless control and does not use such a speed sensor. Patent Documents 1 and 2 disclose a motor controller that performs speed sensorless control for an induction motor.
For example, a motor controller disclosed in Patent Document 2 estimates a primary frequency and a slip frequency of an induction motor from an actual current value (a current FB value) of the induction motor, estimates a rotation speed of the induction motor by subtracting a slip frequency estimation value from a primary frequency estimation value, and drives and controls the induction motor on the basis of this rotation speed estimation value.
Such a motor controller has advantages in a low cost and a small size since the motor controller does not have a speed sensor. Moreover, since wiring for the speed sensor is not necessary, it is possible to enhance water-repellent performance of the induction motor.
Patent Document 1: Japanese Patent No. 5435252
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2013-240194